How many time should the phone vibrate....no joke :-)

Just came from android so I am not sure if this is right, when you choose ring and vibrate should it do both all the time a person calls, I ask because mine vibrates 1 or 2 times while the ring tone plays but stops vibrating after its done it just at the start of the call.
On silent/vibrate only, it will vibrate until I answer or they stop calling.
I am used to a phone vibrating all the time the music plays, not just once or twice.

Well from messing about it seems if the tune (nokia shorter) starts it will vibrate then stop, when the tune loops around to start again it vibrates again......problem with this is longer tunes vibrate at the start and then...well it might not do it again, no doubt you answer it before it gets a chance to loop.
Seems odd that it needs the loop before it will vibrate again rather than just keep going.